Category: CCIE R&S Written Overview

This topic describes the functions of pipes in the Cisco TelePresence Video Communication Server (VCS).

A pipe defines the bandwidth limitations between two subzones or between a subzone and a zone.

A pipe applies bandwidth limits to links. By configuring subzones, links, and applying pipes to links, you can create a model of the physical network and its bandwidth limits on network connections such as WAN links. You can apply bandwidth restrictions per call and for the total bandwidth that goes over a link.

When calls are placed between endpoints in different subzones, you can control the bandwidth that is used on each link that is along the path between the two subzones.

First, you must create one or more pipes and configure them with the desired bandwidth limits. Then you must assign the pipes to the links to apply the desired limits. All calls that traverse one or more links that have a pipe applied must find enough available bandwidth on all links that are involved in the call. This implementation ofCAC is similar to Enhanced Location CAC in Cisco Unified Communications Manager.

Pipe Bandwidth Restrictions: Example

This section shows an example of bandwidth restrictions that are applied to links via pipes.

The figure shows an example of a call where pipe bandwidth restrictions apply.

Endpoint 1 calls endpoint 3 at 2 Mbps, but the bandwidth is downsized to 256 kbps because of the Per Call pipe limitation that is applied to the link between the subzones that are involved in the call. If there was no pipe applied to the link, 512 kbps of bandwidth would be used for the call because this bandwidth is the maximum bandwidth that is permitted, based on the bandwidth limits that are configured at the two subzones.

If another call was made between the default subzone and subzone SL, 256 kbps of bandwidth would be used for the second call. A third call between the two subzones would fail, but not because of the total bandwidth limit that is configured at the pipe (2048 kbps), but because of the In&Out bandwidth limit that is configured at the default subzone (512 kbps).

*To be honest the video for this lesson was extremely painful. I have without a doubt identified my weakest area of the CCIE material. Just look at these notes… what a beast!! Ciscos recommend reading on Multicasting is this badboy:

I think for this particular topic I will really need to get into the book and then go back to the video. It surprised me how detailed this ‘overview’ really was.. The problem as well is I have never touched any kind of multicasting IPv4 network.. so to be an expert at this topic is currently way off!!

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IP Multicast

Multicast Section Objectives

• Understand the components of…

– Multicast Addressing

– Multicast Control Plane

– Multicast Data Plane

IPv4 Multicast Addressing

• IPv4 multicast uses Class “D” Addresses

– 224.0.0.0/4 (224.0.0.0–239.255.255.255)

• Includes reserved ranges

– Link-local Addresses

• 224.0.0.0/24 (224.0.0.0 – 224.0.0.255)

– Source Specific Multicast

• 232.0.0.0/8 (232.0.0.0 – 232.255.255.255)

– Administratively Scoped

• 239.0.0.0/8 (239.0.0.0 – 239.255.255.255)

Multicast Control Plane

• Multicast control plane used to determine

– Who is sending traffic and to what group(s)

– Who is receiving traffic and for what group(s)

– How traffic should be forwarded when it is received

• The Multicast “Tree”

• Control plane is built with a combination of

– Host to Router communication (IGMP)

– Router to Router communication (PIM and MSDP)

Multicast Data Plane

• Once the tree from sender to receiver(s) is built, traffic begins to flow

• Before forwarding, Data Plane checks occur

– Reverse Path Forwarding (RPF) check

• Was traffic received on the correct interface?

– Multicast Routing Table

• What interface(s) should I forward the packets out?

Control Plane – IGMP

• Internet Group Management Protocol

– Used for receiver to signal routers on the LAN that it wants traffic for a specific group

• IGMP host signals membership to router via Report

– IGMPv1/v2 supports only group specific joins

• (*,G) Report

– IGMPv3 supports group and source specific joins

• (S,G) Report

• IOS Router listens for IGMPv1/2 when PIM is enabled

Control Plane – PIM

• Protocol Independent Multicast

– Used for routers to signal each other how to build the Multicast Tree

• “Protocol Independent” because it does not advertise its own topology information

– Implies IGP already runs in the network to build a loop-free topology

• IOS runs PIMv2 by default

PIM Modes

• PIM modes control how the tree is built and who receives what traffic